"You know me. And you know, for Randy Altschuler to say that, is just despicable. I've helped thousands of constituents because it's the right thing to do. And I've never asked for anything in return," Bishop says.

"I approve this message because I'm proud of my service to this district, and for Randy Altschuler to say I'm a criminal just shows he'll do anything to get elected," he says.

A GOP source said the Bishop campaign purchased about $59,000 worth of time on cable TV in the district from Aug. 28 to Sept. 10. It's unclear whether that buy is for this ad or for another spot from the Democrat's campaign.

A Bishop spokesman told Roll Call the campaign doesn't disclose the sizes of its ad buys.

Bishop beat Altschuler, a businessman, by an extremely narrow margin in 2010. Roll Call rates the rematch as Leans Democratic.